Electrical apparatus



Sept. 29, 1925; 1,555,495

L. o. GROIQ D AHL ET AL ELEcTRI AL APPARATUS Original iied Dec. 27. 1921 Fly. 1.

Fig. 2.

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. A 4 ATTORNEY Patented Sept. 29, 1925.

UNITED STATES PATENT OFFICE.

LABS O. GRONDAHL, OF PITTSBURGH, AND LESTER E. SPRAY, OF WILKINSBURG, PENNSYLVANIA, ASSIGNORS TO THE UNIO'N SWITCH 82'. SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OLE PENNSYLVANIA.

ELECTRICAL APPARATUS.

Application filed. December 27, 1921, Serial No. 525,098. Renewed February 18, 1925.

To all whom it may concern:

Be it known that we, LARS O. GRoNDAHL and Lns'rnn E. SPRAY, citizens of the United States, residing at Pittsburgh and Wilkinsburg, respectively, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Electrical Apparatus, of which the following is a specification.

Our invention relates to electrical apparatus, and particularly to apparatus for supplying current of one characteristic or another to an energy-consuming device. One particular form to which the invention is well adapted, and the form which we will describe herein, is that of polarity reversing apparatus, by which we mean apparatus for supplying current of one polarity or the other, or in the case of alternating current one instantaneous relative polarity or the other to an energy-consuming device. It is understood, however, that the invention in its broader aspects is not limited to apparatus for this specific purpose.

One feature of our invention is the provision of apparatus for the purpose set forth having no moving parts, the results being accomplished by means of electrical valves or relays which depend for their action on substances the electrical resistance of which varies with variations in temperature.

The present invention is especially well adapted for use in railway signaling systems, although it is not limited to this specific use.

We will describe two forms of apparatus embodying our invention, and will then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view showing a portion of a railway signaling system including one form of polarity reversing apparatus embodying our invention. Fig. 2 is a view showing a modified form of polarity reversing apparatus embodying our invention which may be substituted for the corresponding apparatus in the signaling system shown in Fig. 1.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. l, the reference characters D and D designate the track rails of a railway along which trafiic normally moves in the direction indicated by the arrow, and which rails are divided bysuitable means, such as insulated rail joints 2, to form electrically isolated track sections A-B, B-C, etc.

The rear section B-Cis provided with a signal S located adjacent the entrance end of the section and comprising, as here shown, three electric lamps, G,jY, and R, adapted when lighted to indicate proceed, caution and stop, respectively. This signal is controlled by suitable apparatus which is responsive to reversals. of polarity of current as well as to the presence and absence of current, and such apparatus is in turn supplied with current of one polarity or the other from the track rails of section BC. The apparatus for the immediate control of signal S forms no part of our present invention, and is fully described and claimed in a co-pending application by Lars O. Grondahl, filed on the ninth day of February,1922, Serial No. 535,19d, for railway signaling. Briefly described, this apparatus comprises two electron tubes J a and J each having a filament 13, a grid 14, and a plate 15. The filaments 13 are constantly heated by the secondary 16 of a transformer T through a circuit which will be obvious from the drawing, and the primary 17 of transformer T is connected with a transmission line 4 which is constantly supplied with signaling current by a generator 18. Each electron tube is provided with a grid circuit which is energized from the secondary of a transformer F, the primary of which is connected'across the rails of section BC at the entrance end of the section.

The electron tube J is provided with a plate circuit which passes from the lefthand terminal of the secondary 19 of transformer T through the proceed lamp G, plate, and filament of tube J and common return wire 20, to the middle point of secondary 19. The electron tube J is provided with a similar plate circuit which passes from the right-hand terminal of transformer secondary 19, through the caution lamp Y, the plate, and filament of tube J andthe common return Wire 20, to the middle point of secondary 19. At any given instant the polarities of the grids 14, of the two tubes J and JP, are the same, whereas, at any given instant, the polarities of the plates. 15, of these tubes, are opposite. It

follows thatwhen current of one relative polarity is supplied-to transformer F by the track rails of section BC, the platecircuit for tube rl is conductive,whilethe Y will be extinguished. Whentherelative polarity of the current in the track circuit for section-B'-C is reversed, however, the plate circuit for tube J will be conductive, and the plate circuit for tube J will be noncondu'ctive, so that the caution lamp Y will beilluminatedand the proceed lamp G will be extinguished.

The stop lamp R- is connected with secondary 21 on transformer T and this lamp isfprlovided with-a shunt which includes'the thermosensitive element 6 of a thermosen sitive relay K the heating element 7 of which is connected with the secondary of transformer F." Relay K has a negative temperature coeflicient, that is, the resistance of the thermo-sensitive element 6 decreases withincrease of'temperature. Itfollows that whentrack' section BC is unoccupied, sothat heating element 7 is supplied with current, the resistance of the shunt around the'stop lamp R is so low that thislamp is extinguished, but when section BG is occupied by a car or train, so that thesupplyof currentto the heating element 7 is discontinued-,the resistance of element 6, and, consequently, the resistance of the shunt around lamp R, is increased to such a value that thislamp becomes lighted.

Alternating current of one instantaneous relative polarity or theotheris supplied to the traclrrails of section B-C by a secondary 3 on a transformer T -the primaryof which is connected with the transmission line 4. The middle point of secondary 3- is connected withone track rail D by a wire 5, while the two outer terminals of this secondary; are connected with the other rail D, so that this secondary 3 constitutes ineffect two sources of current reversely connected with the rails of section B' -C. Iii-- terposed between the left-hand terminal of secondary 3 and rail 1)? is the thermo-sensitive-element f a relay or-valve K and interposed between the right-hand terminal and rail D is the thermo-sensit'ive element 6 of another relayor valve K". Relay K has a positive temperature coefficient, that is, the resistance of itselement ti -increases with i-ncrease of temperature, while relay K has a negative temperature coeflicient, that is,- the resistance of its element 6 decreases with isconnected withv a secondary lOon transformer TB, and the flow-of current-in the circuit is governed by a thermo-sensitive relay K? having, a negative.- temperature coefficient, the thermo-sensitive element of which is included in thecircuit .o'fmprimary 9, and the heating element of which is connected with; the track rails of section AB. These rails are supplied with current by secondary 11 of a transformerT;

The operation of the pole-changing apparatus is as follows-z 'When track section AB is unoccupied, theresistanceof relay K is low, so that current of considerable value flows in the primary 9"oftransformer E with the result that relays K and K are energized. The resistance of relay K" is then high and that of-relay K is low, so thatcurrent is supplied to the track railsof section B'@ from the right-hand half of transformer secondary 3, the instantaneous relative polarity of this current is suclr as to cause lamp G ofsignal S to be lighted. When section A'B is occupied by a-car ortrain, however,- the resistance of relay K is maximum, so that a minimum amount of current is supplied toprimary 9 of transformer'E and relays K and K are then ole-energized Under this condition, the resistance of relay K* is low and the resistance-0frelay IQ is high, so that current is supplied to the rails of section B-C' b'ythe left-hand half of transformer secondary 3, and the instantaneous relative polarity of this current is,- of course, opposite to the instantaneous relative polarity of the current supplied bythe right h'and half of secondary 3*; the caution lamp Y'of-signal SC is then li'ghted, and the proceed lamp G is extinguished.

Referring now to Fig Q, the apparatus here shown is similar tothat shown in Fig. 1 except that both thermo-sensitive relays K? and K have negative temperature coeflicients. Current is at times supplied to the heating element 7 of relay Kt'fr'om secondary 10, the circuit for whichalso includes the thermo-sensitive relay K andthe primary 9'of transformer E The secondary 8 of transformer E is connected in; series with the-heating element? "ofrelay K and a' secondary 12 on transformer T ,the two secondaries 12 and 8 being connected in such-manner thattheyoppose each other. hen section-AB*is occupied by a caror train, the resistance of relay K? is high, so that a minimumamount of current is supplied to primary 9iand heating elemfent 7 of relay K withthe result that rela'y K is deenergized. Secondary l2-then supplies cur rent to heating element 7 of relay K so that this relay is energized, and,- consequently, current is supplied to-track section 13 C by the-right-hand half of secondary 35 When section A-B is unoccupied, however, re

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lay K is energized, so that a maximum amount of current is supplied by secondary 10 to primary 9 and the heating element of relay K, whereby this relay is energized. The current induced in the secondary 8 of transformer E then neutralizes the current supplied by secondary 12, so that relay K is de-energized. Current is then supplied to section B-C from the left-hand half of transformer secondary 3.

Although we have herein shown and described only two forms of apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. Polarity controlling apparatus comprising two sources of current reversibly connected with an energy-consuming device, thermo-sensitive relays interposed in such connections, and means for supplying current to said relays.

2. Polarity controlling apparatus comprising two sources of current reversely connected with an energy-consuming device, two thermo-sensitive relays each having a negative temperature coefiicient interposed between said device and said two sources respectively, and means for supplying current to one or the other of said relays.

3. In combination, two sections of railway track, two sources of current reversely connected with the rails of the rear section, thermo-sensitive relays interposed between said sources and said rails, and means governed by trafiic conditions in the forward section for controlling the energization of said relays.

i. In combination, two sections of railway track, two sources of current reversely connected with the rails of the rear section, two thermo-sensitive relays each having a negative temperature coefficient interposed between said track rails and said two sources respectively, and means controlled by traffic conditions in the forward section for supplying current to one of said relays or the other according as the forward section is occupied or unoccupied.

5. In combination, two sections of railway track, two sources of current reversely connected with therails of the rear section, thermo-sensitive relays interposed between said sources and said rails, a track circuit for the forward section including a third thermo-sensitive relay, and means controlled by said third relay for governing the supply of heating current to the first two relays.

6. In combination, a plurality of different sources of current connected with a currentconsuming device, and thermo-sensitive relays interposed in the connections between said sources and said device.

7. In combination, a plurality of sources of current displaced in phase and connected with a current consuming device, and thermo-sensitive relays interposed in the connections between said sources and said device.

8. In combination, two sections of railway track, two sources of alternating current displaced in phase and connected with the rails of the rear section, thermo-sensitive relays interposed between said sources and said rails, and 'means governed by traffic conditions in the forward section for controlling the energization of said relays.

In testimony whereof we afiix our signatures.

LARS O. GRONDAHL. LESTER E. SPRAY. 

